An example of onboard devices mounted on a vehicle includes a power control unit. For example, a power control unit used in a hybrid vehicle (HV) includes equipment elements such as an electronic control unit (ECU), an inverter, a capacitor, and a voltage converter (DC/DC converter). These equipment elements are accommodated in respective housings, and the housings are stacked to constitute a single housing for the power control unit.
As to such an onboard device mounted on a vehicle, internal equipment elements need to be prevented from damage caused by entry of water into the device. Particularly, an adequate waterproofing measure needs to be taken against the entry of water into an interior portion of the device through a gap formed at an overlapping portion located on a casing of the onboard device.
PTD 1 (Japanese Patent Laying-Open No. 2007-245940) relates to a structure of an onboard electronic equipment element. According to the disclosed structure, either a casing or a cover has a sealing material retaining groove in an overlapping region located between the casing and the cover, and the groove is filled with a sealing material.
PTD 2 (Japanese Patent Laying-Open No. 2010-121662), PTD 3 (Japanese Patent Laying-Open No. 2002-257241), and PTD 4 (Japanese Patent Laying-Open No. 2000-240798) disclose tri-face sealing structures employed in an overlapping portion located between a cylinder block and a cylinder head.